In order to optimize consumption during the operation of vehicles powered by internal combustion engines, especially hybrid vehicles, it is quite common practice to allow the vehicle to glide over certain distances while free-wheeling without propulsion, optionally even with the internal combustion engine switched off. A typical termination condition of this drive state is the actuation of the brake pedal or the actuation of rocker switches on the steering wheel, whereby the drive changes over to the propulsion mode of operation, optionally after switching on the internal combustion engine.
The termination can also be linked to other conditions.
For example, European patent specification EP 2 620 339 B1 discloses a control unit for the gliding mode of operation of a hybrid vehicle with the internal combustion engine switched off. In order to reduce the fuel consumption and to increase the driving comfort of the hybrid vehicle, the hybrid vehicle can be operated in a free-wheeling state with the internal combustion engine switched off. A termination condition of this state is fulfilled when the brake pedal is actuated so strongly that the hybrid vehicle is decelerated beyond a prescribed deceleration threshold is effectuated. Another termination condition comprises the vehicle speed falling below a speed threshold.
For example, German patent application DE 10 2010 062 756 A1 describes a motor vehicle with an evaluation unit for recognizing a braking intention on the part of the driver before the brake pedal is actuated, so that, as a function of the intention, the gliding mode of operation or the propulsion mode of operation is activated, or else a switch is made between these modes of operation. A condition is considered to be the duration of the presence of an intention to brake or a preparedness to brake: if the intention to brake or the preparedness to brake is present for a duration that is longer than a prescribed threshold, then the propulsion mode of operation takes place. If only a duration that is shorter than the prescribed threshold is present, then the gliding mode of operation becomes active.
A drawback is that the described solutions do not permit an intentional changeover between various drive states of the hybrid vehicle.